Device for securing a flexible printing plate to a cylinder of a rotary printing press



July 23, 1968 J. BOHM 3,393,638

DEVICE FOR SECURING A FLEXIBLE PRINTING PLATE TO A CYLINDER OF A ROTARY PRINTING PRESS Filed Sept. 27, 1966 United States Patent 3,393,638 DEVICE FOR SECURING A FLEXIBLE PRINTING PLATE TO A CYLINDER OF A ROTARY PRINT- ING PRESS Josef Biihm, Waldbuttelbrunn, near Wurzburg, Germany,

assignor to Schnellpressenfabrik Koenig & Bauer Aktiengesellschaft, Wurzburg, Germany Filed Sept. 27, 1966, Ser. No. 582,360 Claims priority, application Germany, Oct. 2, 1965, Sch 37,811 1 Claim. (Cl. 101415.1)

ABSTRACT OF THE DISCLOSURE A device for securing a flexible printing plate to a printing cylinder and for adjusting this plate so as to be in tangential register with an adjacent printing plate, wherein this plate encompasses the entire printing cylinder with the exception of a very narrow gap on which no printing can be carried out and its ends are provided with straight arms which are formed by the bent-over ends of the plate and these arms are gripped by a pair of clamping jaws and are held in a fixed position thereon by an intermediate resilient strip, and wherein these jaws may by very simple mechanical means be either drawn toward each other so as to tighten the printing plate on the cylinder or both jaws together with the arms may be shifted in one peripheral direction or the other on the cylinder by tightening one jaw and releasing the other jaw so as to shift the entire printing plate along the peripheral surface of the cylinder until it is in exact register with the adjacent printing plate.

The present invention relates to a device for securing a flexible printing plate to a printing cylinder of a rotary printing press.

Most of the devices which have been employed for this purpose prior to this invention have been in the nature of turnbuckles or the like which have the disadvantage that they take up a relatively large section of the circumference of the printing cylinder and that this section forms a gap on which no printing can be carried out. Consequently, there is a considerable waste in paper.

It is the principal object of the present invention to provide a device for securing flexible printing plates to printing cylinders which overcomes the disadvantages of these turnbuckle devices by tightening a flexible printing plate on a printing cylinder by means of a pair of clamping jaws which are pivotable about axes extending parallel to the axis of the printing cylinder and the opposite clamping surfaces of which act upon the bentover ends of the printing plate and permit these ends to be drawn together so closely that only a narrow gap remains between them.

Although a number of similar devices have previously been disclosed, they were usually either of a rather complicated construction or not reliable in operation, or they were diflicult to manipulate so that the operation of applying and tightening a flexible printing plate on a printing cylinder required a considerable length of time. Most of these devices also rendered it impossible to adjust the flexible printing plate so as to be in tangential register with an associated plate or to make the gap between the ends of the printing plate sufliciently narrow.

It is therefore a further object of the invention to provide a securing device of the above-mentioned type which also overcomes the disadvantages of all similar devices and is of a simple and reliable construction and permits a flexible printing plate to be very easily applied and tightened on a printing cylinder, the gap between the bent-over Patented July 23, 1968 ends of the printing plate to be made very narrow, and the tangential register between one of these plates and an associated printing plate to be very quickly and accurately adjusted.

For attaining these objects the invention provides that the ends of the flexible printing plate only need to be bent over once and that a cord or the like of an elastic material is inserted between these ends which extends substantially parallel to the axis of the printing cylinder and presses the arms formed 'by the bent-over ends firmly against the clamping jaws which are preferably provided with roughened or serrated gripping surfaces. Since the ends of the printing plate are bent over only once, this plate may be easily installed on and removed from the printing cylinder and easily adjusted in register in the tangential direction relative to an associated printing plate.

For this purpose, one of the clamping jaws is tightened, while the other jaw is released so that both arms of the printing plate together with the printing plate itself are shifted in one or the opposite peripheral direction on the the printing cylinder. Since the bent-over ends of the printing plate are only separated by an elastic cord or the like, the gap remaining between these ends on which no printing can be carried out is very narrow.

These and numerous additional features and advantages of the present invention will become more clearly apparent from the following detailed description thereof which is to be read with reference to the accompanying drawing which shows a cross section of a part of a printing cylinder and the printing plate thereon and of the securing or clamping device according to the invention.

As illustrated in the drawing, the clamping device according to the invention comprises a pair of clamping jaws 3 and 4 which are provided with opposite clamping surfaces 7 and 8 and are disposed within an axially extending recess 1 of the printing cylinder 2 and are ivotally mounted on a pair of shafts 5 and 6 which extend parallel to the axis of cylinder 2 and are mounted on end discs, not shown, on both ends of the printing cylinder. Between the bent-over ends forming straight arms 9 and 10 of the flexible printing plate 11 a cord 12 or the like of an elastic material is inserted which extends along the entire width of the printing plate 11 and presses these ends resiliently against the clamping surfaces 7 and 8 of the clamping jaws 3 and 4.

For clamping the printing plate 11 with the required tension upon the printing cylinder 2, a setscrew 17 is adapted to act upon the end of lever 18 carrying the clamping jaw 3 so as to pivot the same about the axis of shaft 5, while the other lever 15 carrying the clamping jaw 4 and pivotable about the axis of shaft 6 is acted upon by a spring-loaded plunger 16 which acts upon the lever 15.

For releasing the printing plate 11, an eccentric 14 may be turned about a shaft 13 so as to act upon the lever 15 on shaft 6 and thus upon the clamping jaw 4.

The tangentail register between the printing plate 11 and the associated printing plate, not shown, may be adjusted by setscrew 7. When this setscrew is turned so as to apply upon lever a force in excess of the spring force of plunger 16 acting upon lever 15, the pivoting movement of lever 18 and jaw 3 will be transmitted through the bent over ends or the arms 9 and 10 on the printing plate and the intermediate elastic strip 12 to jaw 4 and lever 15 against the action of the spring-load plunger 16 with the result that both ends 9 and 10 on the printing plate will be shifted in the same direction and printing plate 11 will be shifted peripherally in one direction along cylinder 2. The reverse movement of printing plate 11 on cylinder 2 will occur when setscrew 17 is released so as to exert a smaller pressure upon lever 18 than that whichisexerted' by plunger 16 upon the other level: 1.5. i 1 was. v

The pivotally monuted levers 15 and 18 carrying the jaws 4 and 5, respectively, serve as means on the cylinder for pivoting the clamping jawsjf 4 and S. vThe eccentric 14 on shaft 13 acting on lever 15 which is biased by the spring loaded plunger 16 and the setscrew v17,ac ting on lever 18 may be termed the mechanical means that act upon the-levers 15 and 18, respectively.

The sides of the clamping jaws' 3 and 4 facing each other are provided underneath the clamping surfaces? and 8. with toothlikeprojections 19 on each clamping jaw which engage in-to corresponding recesses in the other jaw and prevent, the elastic cord 12 from falling into the, recess 1 when theclamping jaws are released, and the clamping surfaces 7 and 8 of jaws 3 and 4 are provided with serrations or the liketo insure-a firm grip on the'bentover ends 9 and 10 of printing plate 11.

Although myinvention has been illustrated and described withreference to the preferred embodiment thereof, I wish to have itunderstood that it is in no way limited to the details of such embodiment but is Capable of numerous modifications within the scope of the appended claim.

Having thus fully disclosed my invention, what- I claim 1. A device for securing a flexible printing plate to a printing cylinder of a rotary printing press comprising a pair of clamping jaws disposed within a recess in said cylinder, means on said cylinder in operative engagement with said clamping jaws for pivoting said clamping jaws relative to each other about axis extending parallel to the axis of said cylinder, each of said clamping jaws having a clamping surface facing that of the other clamping jaw, said printing plate having bent-over ends form ing straight arms extending along substantially the entire width of said printing plate and engaging into said recess between said clamping surfaces, the corners between said plate .and said straight armsbeing adapted when said clamping jaws are tightened to be separated from each other by a narrow gap, a strip of elastic material inserted between and adapted to press against said straight arms so as to hold the same in a fixed position on said jaws and extending substantially along the en-tirewidth of s'aid straight arms, and mechanical means adapted to "act upon each of said means on said cylinder f or"pivoting said clamping jaws so as to pivot' said clamping jaw to each other for tightening or releasing tlh'efsa v for thereby moving said straight arm's toWajrdLand' away from each other when at least onerofsaid, mechan,ical means is tightened or released, .said mechanical means being further adapted to'shift said straight arms together with said printing plate in the same peripheral direction relative to said cylinder when one of said mechanical means is tightened and the-other is released for adjusting the tangential register between said printing plate and an adjacent printing plate, each of said clamping-jaws having adjacent projections and recesses underneath the free ends of said arms, said projections on one jaw being adapted to engage into said recesses in the other j'aw for preventing said elastic strip from falling into said recess insaid cylinder when said clamping jaws are released;

References Cited I UNITED STATES PATENTS Lang 101415.'1 X

ROBERT E. PULFREY, Pram Examiner.

F. A. WINANS, Assistant Examiner. 

